Problem: Simplify the expression. $(n-6)(-n-7)$
First distribute the ${n-6}$ onto the ${-n}$ and ${-7}$ $ = {-n}({n-6}) + {-7}({n-6})$ Then distribute the ${-n}.$ $ = ({-n} \times {n}) + ({-n} \times {-6}) + {-7}({n-6})$ $ = -n^{2} + 6n + {-7}({n-6})$ Then distribute the ${-7}$ $ = -n^{2} + 6n + ({-7} \times {n}) + ({-7} \times {-6})$ $ = -n^{2} + 6n - 7n + 42$ Finally, combine the $x$ terms. $ = -n^{2} - n + 42$